386 ©. 8. Lyman’s new form of Wave apparatus. 
of adjacent crank arms is one eighth of a circle, as shown in 
the figure. The cranks in each vertical set have their posi- 
tions always alike. The number of cranks, whether taken hor- 
izontally or vertically, is arbitrary—a matter of convenience in 
construction. The synchronous revolution of the cranks is 
effected by means of any suitable mechanism; such as, equal 
toothed wheels on the several axes, with alternate idle wheels 
equally represents a wave whose length is 36 feet and height 4 
feet, with period 2*63; and similarly, for other proportional 
ensions. : 
Among the particular points, in wave phenomena, which are 
elucidated by this apparatus, may be enumerated the following: 
1. The undulating swrface-profile. This is shown in the 
motion of the upper flexible wire, which presents a contintous 
contour line, of the exact curvature, throughout, of a true nor- 
mal wave; instead of a broken contour, of arbitrary form, by 
means of rising and falling balls, as in the ordinary wave ap- 
posed of particles in a state 
Dae, | Mp 
